Space charge formation at the interface between a charge transport layer and a polyester film

The organic photoconductor structure used in a copying machine consists of electron-conductive and ion-conductive layers, a charge generation layer, and a charge transport layer. We applied the pulsed electroacoustic method, which has been used to evaluate HV insulation, to measure the space charge behavior of the charge transport layer coated on a polyester film. On the surface of the charge transport layer, various electrodes were evaporated. An internal space charge accumulated at the interface between the charge transport layer and the polyester film under a dc electric field. We show that the charge distribution is formed by the injection of holes from the anode and by the surface charge, and that the hole injection is influenced by the anode material.